Add CAN support

[manchoz]

It would be nice to integrate CAN bus support in the build, either as integrated drivers or modules.

There are many CAN adapters based on different HW bus technologies, starting from UARTs to SPI. Pretty popular, inexpensive, and open source devices include CAN USB adapters like CANable and Candlelight, which are supported by the slcan and gs_usb drivers, respectively. PEAK System PCAN-USB adapters are also popular and considered one of the reference implementations.

[lool]

Thanks for listing specific USB devices that we want to enable (CANable and Candlelight); is this request about turning tweaking the kernel config? Could you list the specific minimum changes that would be needed?

Once we make these changes, someone plugs their USB device and it works? Are any other software changes needed?

[quaresmajose]

Thanks for listing specific USB devices that we want to enable (CANable and Candlelight); is this request about turning tweaking the kernel config? Could you list the specific minimum changes that would be needed?

Yes, this requires kernel config changes. We need to add the socketcan networks stack as well as some IO driver to look at the electrical signals on the bus.

Once we make these changes, someone plugs their USB device and it works? Are any other software changes needed?

We need some user space tools like the canutils but I can investigate more to understand the satus of the can bus on linux.
The slcan is to attach can drivers that comunicates over rs232, the gs_usb is a new tool for me.

[manchoz]

Yes, this requires kernel config changes. We need to add the socketcan networks stack as well as some IO driver to look at the electrical signals on the bus.

Once we make these changes, someone plugs their USB device and it works? Are any other software changes needed?

Depending on the driver, i.e., the attached device, some command needs to be issued to create the CAN interface. Being CAN supported in a similar way to networking devices (because of SocketCAN), interfaces can be configured with iproute tools such as ip.

The can-utils package is recommended.

We need some user space tools like the canutils but I can investigate more to understand the satus of the can bus on linux. The slcan is to attach can drivers that comunicates over rs232, the gs_usb is a new tool for me.

slcan is for devices which expose an UART interface towards the host over which the slcand daemon creates a CAN interface. gs_usb is used with the Candlelight firmware and is natively SocketCAN compatible. Every CAN devices then attaches to a CAN bus (which is typically made by three wires, CANH, CANL, and GND.)